Conventional linear actuator fixes a threaded pole in front end of the motor, and an escalating threaded nut, mounted on the outside edge of the threaded pole, moves in axial direction while the threaded pole rotates diametrically; whereas the rotating speed of conventional motor is extremely fast, so that linear actuator fixed a set of gear slow-down device between output shaft and threaded pole to buffer the rotating speed of the threaded pole.
Refer to FIG. 4 and FIG. 5, conventional linear actuator primarily comprises a motor body a and an output shaft a1 which mesh with first big decelerating gear b in the edge of front side; whereas the first big decelerating gear b is disposed under one side of output shaft a1, and in the front center of big decelerating gear b fixes a first small decelerating gear b1 which meshes with second big decelerating gear c; whereas the second big decelerating gear c is disposed under the other side of output shaft a1 beside the first big decelerating gear b, and in the center of second big decelerating gear fixes a second small decelerating gear c1 which meshes with the third big decelerating gear d; In front end of shaft center of the third big decelerating gear d fixes a threaded pole d1 with an escalating threaded nut d2 mounted on.
As mentioned above, the output shaft a1 of conventional linear actuator drives the first big decelerating gear b to rotate, and rolls the first small decelerating gear b1 simultaneously, and therefore takes advantage of the mechanic functionality of the number of the teethes of output shaft a1 less than that of the first big decelerating gear d to gain the purpose of slowing down the speed; similarly, the mesh between first small decelerating gear b1 and the second big decelerating gear c, and the second small decelerating gear c1 together with third big decelerating gear d are also designed to meet the purpose of slowing down the rotating speed.
Accordingly, the mesh point between gears of conventional linear actuator only in one part makes the actuation strength concentrate on one or two gears. In order to prevent concentrating strength from causing collapse, usage of better enduring material quality and weight and volume emphasis will increase the manufacturing cost and weaken the market competition.